In the conventional manual transmission synchronizer, the coupling sleeve is moved by the driver's shift lever operation to change speeds, and the coupling sleeve chamfer and balk ring chamfer come into contact. Then, the movement of the coupling sleeve is stopped, the cone surface of the balk ring pushes the cone surface of the clutch gear, thus generating a synchronizing torque (synchronizing force), resulting in rotation synchronization of the balk ring and the synchro hub (for example, refer to Unexamined Japanese Patent Application Publication No. H6-33952 and Unexamined Japanese Utility Model Application Publication No. H6-8824).